Abstract In their recent paper, Machalski and Malchyk, 2019, present a paleobathymetric model proposed relations among main facies types, including opoka and chalk, along a perpendicular to the shore. The model is seemed to be a pioneering one based on paleoecological and taphonomical data from the successions from Poland and western Ukraine. However, speaking about lithofacies, the authors do not take into account such crucial factors as mineral composition of rocks and origin of silica in the basin. “Camouflaged” pyroclastic material which is evidence of volcanic ash falls, could be among major contributors to mineral composition of opokas and among minors of chalks. Thus, considering this factor could be essential to sediment accumulation the paleobathymetric model would not face mismatches revealed in different parts of the basin. More research (including quantitative XRD and electron microscopy analysis) is necessary to study precise mineral composition and peculiarities of rock microfabrics in order to understand the proper origin of opokas and chalks, making a basis for more reliable paleobathymetric model of distribution of chalks and opokas in the Late Cretaceous European Basin.

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评论 M. Machalski 和 O. Malchyk 撰写的“晚白垩世欧洲盆地中 opoka 和白垩的相对测深位置”[白垩纪研究。102 (2019) 30-36]

摘要 在他们最近的论文中，Machalski 和 Malchyk，2019 年，提出了一个古水深模型，提出了主要相类型（包括 opoka 和白垩）沿垂直于海岸的关系。该模型似乎是一个开创性的模型，它基于来自波兰和乌克兰西部的演替序列的古生态学和土壤学数据。然而，在谈到岩相时，作者并没有考虑到盆地中岩石的矿物组成和二氧化硅的起源等关键因素。“伪装”火山碎屑材料是火山灰坠落的证据，可能是造成 opokas 矿物成分的主要因素之一，也可能是少数粉笔的主要贡献者。因此，考虑到这一因素可能对沉积物积累至关重要，古水深模型将不会面临盆地不同部分所揭示的不匹配。